Optimal blind channel estimation for DQPSK demodulation
a blind channel and demodulation technology, applied in the field of blind channel estimation, can solve the problems that the practical dqpsk demodulation approach does not attempt channel estimation, and achieve the effects of improving signal-to-noise ratio (snr), improving dqpsk demodulation performance, and low complexity
Active Publication Date: 2012-10-23
QUALCOMM INC
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Benefits of technology
This method improves DQPSK demodulation performance by achieving a 1 dB to 3 dB improvement in signal-to-noise ratio for a bit error rate of less than 0.07, is theoretically optimal, and can be applied to existing standards like ISDB-T without pilot symbols, while maintaining low computation complexity for practical implementation.
Problems solved by technology
However, as noted above, practical DQPSK demodulation approaches do not attempt channel estimation due to a lack of sufficient reference symbols in this form of transmission.
Method used
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[0020]While the present invention is described herein with reference to illustrative embodiments for particular applications, it should be understood that the invention is not limited thereto. Those skilled in the art with access to the teachings provided herein will recognize additional modifications, applications, and embodiments within the scope thereof and additional fields in which the invention would be of significant utility.
[0021]FIG. 1 is an illustration of a DQPSK modulated communications receiver to which embodiments of the current invention may be employed. A typical communications receiver 100 comprises an antenna 110, a front end 120, a channel equalizer 130, a demodulator 140, and an error correction decoder 150. A communications signal that has passed through a communications channel from transmitter to receiver is captured by the antenna 110, and is turn coupled to the receiver's front-end 120. The front-end 120 provides one or more of the following functionalities:...
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An apparatus and method are described that provide an optimal blind channel estimation approach for a differential quadrature phase shift keying (DQPSK) modulation communication receiving system. The described blind channel estimation technique takes advantage of the characteristics of DQPSK constellations and the fact that estimates of relative channel phase distortion, and not absolute channel phase distortion, are sufficient for a DQPSK demodulation scheme. The described channel estimation approach provides low complexity, offers improved demodulation performance, and is theoretically optimal. It is particularly useful in existing DQPSK-based communications protocols that do not provide sufficient reference symbols for channel estimation.
Description
FIELD OF THE INVENTION[0001]The present invention relates to a method and apparatus for blind channel estimation, and more specifically to the optimal blind channel estimation for differential quadrature phase shift keying (DQPSK) modulation communication systems.BACKGROUND ART[0002]The need for high speed robust communications systems has grown dramatically in recent years. Such a demand has been fueled by the need to support various communications market segments, e.g., ever increasing numbers of voice calls, higher information transfer rates, better connectivity to the Internet. Both consumer and business market segments have witnessed unparalleled increases in growth, and such growth is predicted to continue for the foreseeable future. In theory, communications systems could accommodate the demand for increased data throughput by securing additional bandwidth over which to transmit. However, bandwidth is a limited resource and in most cases is limited by regulation. Accordingly,...
Claims
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IPC IPC(8): H03K9/00
CPCH04L27/389H04L25/0202
Inventor QI, YIHONGTOUZNI, AZZEDINE
Owner QUALCOMM INC